Master-slave micromanipulator method

ABSTRACT

A method based on precision X-Y stages that are stacked. Attached to arms projecting from each X-Y stage are a set of two axis gimbals. Attached to the gimbals is a rod, which provides motion along the axis of the rod and rotation around its axis. A dual-planar apparatus that provides six degrees of freedom of motion precise to within microns of motion. Precision linear stages along with precision linear motors, encoders, and controls provide a robotics system. The motors can be remotized by incorporating a set of bellows on the motors and can be connected through a computer controller that will allow one to be a master and the other one to be a slave. Position information from the master can be used to control the slave. Forces of interaction of the slave with its environment can be reflected back to the motor control of the master to provide a sense of force sensed by the slave. Forces import onto the master by the operator can be fed back into the control of the slave to reduce the forces required to move it.

GOVERNMENT RIGHTS

The present invention was made with United States Government supportunder Contract No. DE-AC04-94AL85000 awarded by the U. S. Department ofEnergy. The Government has certain rights in this invention.

This is a divisional of U.S. patent application Ser. No. 08/827,144filed Mar. 27, 1997, incorporated herein by reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a micromanipulator and a controllertherefor, with six degrees of freedom, for enhanced precisionpositioning.

Most conventional X-Y stages are built in combination to providemultiple axes of motion and do not have coordinated axes. In otherwords, many commercial manufacturers stack one linear stage in the Xdirection upon a second linear stage in a Y direction and a third linearstage in a Z direction, in order to provide three degrees of freedom.These conventional systems do not provide software controls to allow theuser to move the stages simultaneously, in order to get more than justindividual joint-type motions. Coordinated motion is especiallyimportant when attempting to produce something as complex as drawing acircle on a piece of paper. As a non-limiting example, most peopleunderstand the principles behind an Etch-a-Sketch, which is controlledwith two knobs, one for each of the of X and Y directions. It is verydifficult to provide a circle type motion with an Etch-a-Sketch becauseboth the X and the Y axes must be coordinated. This is the type ofmotion that the present invention simplifies and provides. Also, thepresent invention not only controls the position, but controls velocityand force as well.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an apparatusand method for a dual stage coordinated X and Y and position andorientation output for use as a master-slave micromanipulator. Thecoordinated X-Y stage with four degrees of freedom comprises a firstplanar structure comprising a first X and first Y controlled set, asecond planar structure comprising a second X and second Y controlledset wherein the second planar structure is stacked on top of the firstplanar structure, an arm gimbaled to the first planar structure andgimbaled to the second planar structure and a head affixed to the armcomprising a coordinated X and Y position and orientational output. Thepresent invention further comprises a fifth degree of freedom, the fifthdegree of freedom comprising structure for movement along the axis ofthe arm. The apparatus of the present invention further comprises asixth degree of freedom of motion; the micromanipulator has six degreesof freedom of motion. The sixth degree of freedom can comprise rotationabout the axis of the arm. The first planar structure can comprise a topplane float.

The micromanipulator comprises a master dual planar structure comprisinga first coordinated and simultaneous X and Y and orientational output, aslave dual planar structure comprising a second coordinated X and Y andorientational output and an apparatus for mimicking and an apparatus forscaling down the first coordinated X and Y and orientational output tothe second coordinated X and Y and orientational output. Themaster-slave design translates, for example, centimeter movements of themaster into micrometer movements of the slave. The first coordinatedoutput can comprise a first gimbaled arm and the second coordinatedoutput can comprise a second gimbaled arm. The apparatus furthercomprises structure for movement along an axis of the first gimbaled armand the apparatus for mimicking and the apparatus for scaling furthercomprise scaling and mimicking the movement along an axis of the secondgimbaled arm. The apparatus further comprises a structure for rotationabout the axis of the first gimbaled arm and the apparatus for mimickingand the apparatus for scaling further comprise scaling and mimicking therotation along an axis of the second gimbaled arm. The apparatus formimicking comprises a push-push operation micromanipulator. Thepush-push apparatuses comprise hydraulic apparatuses. The apparatus formimicking can comprise a member from the group consisting of directdrive motors, drive screws, lead screws, ball screws, and combinationsthereof. One advantage of the present invention is its small size andability to locate the power sources in a remote location. The apparatusfor scaling can comprise a computer. The apparatus further comprises afeedback loop for sending a signal from the second gimbaled arm to thefirst gimbaled arm when the second gimbaled arm contacts a predeterminedsurface, thus enhancing its ability to reflect contact with a surfacefrom the slave back to the master. The invention can further comprise atremor filter. The invention can further comprise means for compensatingfor gravity. The invention can further comprise means for recording andplaying back motion commands.

The method of the present invention for micromanipulation comprises thesteps of providing a master dual planar structure with a coordinated Xand Y and orientational output, providing a slave dual planar structurecomprising a second coordinated X and Y and orientational output andmimicking and scaling down the first coordinated X and Y andorientational output to the second coordinated X and Y orientationaloutput. The method further comprises the step of moving a first gimbaledarm affixed to the master dual planar structure along an axis of thefirst gimbaled arm and mimicking and scaling the movement along an axisof a second gimbaled arm affixed to the slave dual planar structure. Themethod further comprises rotating the first gimbaled arm about its axisand mimicking and scaling the rotation along an axis of the secondgimbaled arm. The step of mimicking comprises providing push-pushapparatuses. The step of scaling comprises providing a computer. Themethod further comprises the step of feeding back a signal from thesecond gimbaled arm to the first gimbaled arm when the second gimbaledarm contacts a predetermined surface. The method further comprises thestep of filtering tremors. The method further comprises the step ofcompensating for gravity. The method further comprises the step ofrecording and playing back motion commands.

The novel features of the present invention will become apparent tothose of skill in the art upon examination of the following detaileddescription of the invention or can be learned by practice of thepresent invention. It should be understood, however, that the detaileddescription of the invention and the specific examples presented, whileindicating certain embodiments of the present invention, are providedfor illustration purposes only because various changes and modificationswithin the spirit and scope of the invention will become apparent tothose of skill in the art from the detailed description of the inventionand claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which are incorporated in and form part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

FIG. 1 is a side view of an embodiment of the present invention;

FIG. 2 is a front view of the top stage of the present invention of FIG.1;

FIG. 3 is a side view of the top stage;

FIG. 4 is a perspective view of the Y axis bearing;

FIG. 5 is a perspective view of the X axis bearing;

FIG. 6 is a side view of the top plane float;

FIG. 7 is a side view of the dual two axis gimbals;

FIG. 8 is a side view of joint five and joint six without the motor;

FIG. 9 illustrates the drive train;

FIG. 10 show a single stage of the drive train; and

FIG. 11 is a block diagram of the overall system of the presentinvention.

FIG. 12 illustrates the combination of the X-Y stage apparatus and drivetrain structure.

DETAILED DESCRIPTION OF THE INVENTION

The overall design of the platform of the present invention is based onthe theory that very precise X-Y stages, which are used in manyprecision applications, such as laser aiming and directing systems X-Ystages that are used for micro positioning stages, can present a basisfor precision motion in six degrees of freedom.

The present invention combines a six degree of freedom platform with acomputer, programmed with software, that connects to another six degreeof freedom platform. The first platform can be used as a joystick, withfour sensors built into each of the axes, and the second platformresponds to commands provided by the first platform. In other words, theuser has his/her hands on the end of a sixth joint on the first system,or master, and he/she is moving the system, thus back driving themotors. The system senses the position and forces at each joint that areimposed by pushing on it. A signal is sent to the computer, the computertakes the force and displacement numbers and sends them to the secondsystem, which is called the slave system. The master system commandsmotion of the motors in the second system in order to generate motionthat basically mimics the first system. This is more commonly known as amaster-slave arrangement. If the slave system contacts a surface, thenit too has positive force sensors that sense the position and forces.The position and forces are sent through the computer back to the mastersystem. The motors in the master system are commanded to move and driveagainst the hand of the person who is holding the device, indicatingthat contact had been made. This is called force reflection or forcereflecting tele-operation. Some of the unique features of the presentinvention are the mechanical platform, which relies on very precisetechnology in a very unique arrangement, and a very unique architecturefor control, which provides a very high bandwidth operation. Currentopen architecture software control technology (e.g.,commercially-available software from Delta Tau, Trellis, and GalilMotion Control) is capable of controlling the robot system in aposition-controlled autonomous environment. (Delta Tau is the name of acompany that sells control solutions for different types ofapplications; Delta Tau offers the preferable commercially-availablesystem. Delta Tau is located at 9036 Winnetka Avenue, Northridge, Calif.91324. Trellis Software & Controls, Inc., is located at 2619 ProductDrive, Suite 106, Rochester Hills, Mich. 48309-3807, a company that wasrecently purchased by Hewlett Packard. Galil Motion Control is locatedat 575 Maude Court, Sunnyvale, Calif. 94086.) The disadvantage in usingcurrent open architecture software is that this application is not justa true autonomous problem. Ideally, external software must be written tointegrate platforms such as these to operate in a master/slavearrangement. Thus, in order to use a typical motion control boardavailable on the open commercial market, additional external computingand control is necessary for these systems to operate in the environmentdescribed. The optimum software configuration for this application is totightly couple the control systems of the master/slave devices on boarda high-performance computing environment. Some algorithms run as high as5000 Hertz to provide smooth, torque ripple-free motion, while othersrun at half of the above rate. This type of performance is not possiblewith generic open architecture controllers without some modifications.

The unique hardware design for the structural elements is comprised oftwo planar actuator sets. One X-Y controlled plane is situated on top ofa second planar X-Y controlled set, which is referred to as a dualplanar design. This dual planar design can be visualized by taking bothhands and arranging them together with palms facing each other, spaced asmall distance apart and slipping a pencil between the fingers of eachpalm, so that they are interconnected through this pencil. As one moveshis/her palms in planar motion relative to each other, in any direction,the pencil motion is controlled. The pencil moves in rotation if thepalms are moved in opposite directions or moves linearly if the palmsmove in the same direction or some variation thereof in order to achievecoordinated motion of the pencil. If the tip of the pencil is placed ona piece of paper, then a drawing is made when the tip changesorientation and position relative to the positions of each of the twoplanes (two palms). This would be the top plane and the bottom plane.For each plane, there is an X-Y control; the top plane has an X-Ycontrol and the bottom plane also has an X-Y control. The stages can bepositioned. The top stage and the bottom stage move throughout theirindividual ranges of motion, X and Y, precisely because of motors andencoders, that are provided on each of the X and Y stages, individually.The top plane represents two axes (X and Y), the bottom plane representstwo more axes (X and Y), adding up to four axes, generating four degreesof freedom. Figuratively, the pencil connects those two planes through aset of two two-axis gimbals. Motion along the axis of the pencil androtation about the axis of the pencil generates the fifth and sixthdegrees of freedom. Therefore, a total of six degrees of freedom is madeup by two X-Y planes which are four degrees of freedom and two moredegrees of freedom which are generated by moving in and out along theaxis of the figurative pencil and around its axis, rotation-wise. Thisis a very unique design for six degrees of freedom.

With this design, one can achieve a minimum of ten microns resolution atthe end of the last joint which is the sixth joint. Applications can berealized in many things that need and require precise motion. Precisemotion is needed, for example, in surgery, micro-surgery in particular,eye surgery, vitreo-retinal surgery, ear, nose and throat surgery,neurosurgery, micro-hand surgery or micro-orthopedic surgery, ingeneral, or any surgery that require microscopes. In essence, thepresent invention provides tools similar to those provided by amicroscope. A microscope provides the ability to magnify a view ofsomething that is very small. The present invention provides basicallythe opposite; it allows motion that is generated on the order ofmillimeters in one's hand to be down scaled to produce micron motions onthe work surface, which allows translation of hand motions in millimeterspace to micron motions within the microscope space. To extend theapplications, the present invention can be used in applications such asmicroelectronics assembly, microelectro-mechanical systems (MEMS)assembly for micron scale gears, motors, and the like. Several companiesare generating MEMS devices using standard electronic fabricationtechniques, however, there are very few methods for actually assemblingthese devices once they are manufactured.

The present invention allows a user to down scale motions and becausethis system is controlled via computer, it also allows the applicationof filters for anomalies such as tremors. Most individuals experience atremor to some level. If, for example, the operator or surgeon has atremor that is due to some neuromuscular limitations, the presentinvention allows filtration of such a tremor if the frequency of thetremor can be characterized.

FIG. 1 shows an overall side view of an embodiment of the presentinvention. The micromanipulator shown has a duplicate set of X and Yplanar structures, top plane control arm 40, also referred to herein asY control arm 40, and bottom plane control arm 50 attached to two longarms which are combined with a gimbal system. Attached to the gimbal arejoint five 70 and joint six 80, which will be discussed in detail below.

Base frame 10 has a U frame shape on its side with top portion 20,bottom portion 30, and back part 11. Top X-Y plane control arm 40 isattached to top portion 20, and bottom X-Y plane control arm 50 isattached to bottom portion 30, as shown. Two plane control arms 40 and50 extend from each of the X-Y planes. Top plane control arm 40 isattached to bottom plane control arm 50. Each plane control arm 40 and50 can move in X and Y directions individually and independently. Topplane float 60 is affixed as shown in FIGS. 1 and 3. As in the previousanalogy, if one has his/her hands together with fingers interlocked onthe pencil so the pencil cannot slip in and out, the hands are spaced ata certain distance when the pencil is perpendicular to the plane of thehands. As one's hands are moved in opposite directions with respect toeach other so that the pencil is no longer perpendicular, the handsapproach each other. Similarly, as top plane control arm 40 moves in anopposite direction with respect to bottom plane control arm 50, topplane float 60 allows for the change in distance between the planes.This is needed to achieve various angles of orientation of joint five 70and joint six 80. The gimbal arrangement will be described later. Thepresent invention is ideally suited to be configured as ahydraulically-controlled system. Hydraulic hoses (or tubes) 14 providewater to the system as shown in FIG. 2. Other configurations can beutilized, such as direct drive motors, screws that drive, based onrotary motors, or other linear actuator systems that deliver veryprecise motion such as lead screws, ball screws which provide linearmotion while also providing back driveability, or linear motors directlydriving the system. The present invention can utilize Belloframdiaphragms, which are rolling edge diaphragms, or bellows which aresimilar to hydraulic cylinders. Hydraulic piston and sleeve cylinderscan also be used. To minimize the size of the total package, the motorscan be removed into a separate unit and connected to hydraulic lines.

FIG. 2 shows a front view of the top stage or top plane of the system.Top portion of base plate 20 is shown attached to base frame 10. Affixedto top portion of base plate 20 is X axis bearing 13 which is a linearbearing that can be a recirculating linear ball bearing or arecirculating cross roller bearing, or any type of bearing with veryhigh precision and which can take high moments. The linear bearing usedin the embodiment shown is a linear ball bearing manufactured by THK. Xaxis bearing 13 is attached to pillow block 18 which is attached to topportion of base frame 20 with four pillow block screws 22. X axisbearing 13 attaches to X axis bearing rail 90, to control arm 21 asshown. This allows control arm 21 to move in the X direction relative tothe top portion of base frame 20 which is stationary. Control arm 21 isattached to two X Belloframs 24. The outside cylinder of X Bellofram 24is shown with an extending center piston 25 attached by hexagonal nut 15and spacer 16 to control arm 21 as shown. Hydraulic hose 14 is attachedto fitting 17 on the back of X Bellofram 24 in order to deliver thewater fluid. There is a duplicate X Bellofram 24 configuration in therear part (not shown) of view of FIG. 2. The reason for these twoBellofram configurations is to act in opposition to each other in orderto provide X motion. The one cylinder pushes to generate leftward motionand the other cylinder pushes to generate rightward motion. This isduplicated on the control drive train, as shown in FIG. 9. Pairs ofBelloframs that are pushed in opposite directions in order to generatepush-push type motion. This entire arrangement relies on compression offluid and does not rely on pulling of the fluid.

A second linear Y axis bearing 41 is attached to control arm 21 with thesame arrangement as described before with pillow block 45 which isattached to control arm 21 and rail 41 which is attached through screws42 to top control arm 40. The previously described Bellofram drive is aduplicate of the aforementioned arrangement. See Y Bellofram 43. Due tothe aforementioned configuration, control arms 21 and 40 provide twostages of series X and Y motion. Rod 47 is shown extending outward fromthe view and provides outward motion. Hydraulic hose 14 is attached to aright angle fitting 19 to provide coupling between the drive train, inFIG. 9, and Y Bellofram 43.

FIG. 3 shows a side view of the present invention. FIG. 3 provides aview of rearward Y Bellofram 43. Pointed in a rearward direction are Ycylinder arm 44, Y hexagonal nut 45, and Y spacer 46, which are attachedto the top control arm 40. Top control arm 40 is attached to top planefloat 60 and to gimbal (not shown). The bottom plane control arm 50 ofFIG. 1 is a mirror image of the top plane control arm 40 as heretoforedescribed. Bottom plane structure is affixed to bottom portion of baseframe 30 as shown in FIG. 1. Therefore, there are two X-Y planes,comprising top plane control arm 40 and bottom plane control arm 50, asshown in FIG. 1, affixed to two sets of gimbals.

FIG. 4 shows a close-up of Y axis bearing 41 that is shown in FIG. 2.There is a stop block 47 attached to Y axis bearing 41, as shown in FIG.4, that prevents over travel.

FIG. 5 shows a close-up view of X axis bearing 13 that is shown in FIG.2. Pillow block screws 22 attach pillow block of X axis bearing 13 andrail of X axis bearing 13 is attached with X axis bearing screws 23 tocontrol arm 21 as shown in FIGS. 2 and 5.

FIG. 6 shows a close-up of top plane float 60 that is shown in FIG. 1.Top plane control arm 40 and bottom plane control arm 50 control X and Ylinear motions. FIG. 6 is a close-up view of the top plane float 60comprising top plane bracket 61 which is attached to top plane controlarm 40 with top plane bracket screws 65. Top plane bracket 61 houseslinear ball bearing 62 which glides on bearing rod 63. Ball bearing 62is attached to top plane bracket 61 with bearing screw 66. Bearing rod63 is attached to end bracket 64 with rod screw 67. End bracket 64 isattached to gimbal bracket 69 with gimbal screw 68.

FIG. 7 shows a close-up view of the dual two-axis gimbals shown bygimbal brackets 69 and 69' of FIG. 6. Gimbal bracket 69 is affixed bygimbal screws 68. X axis bearing assembly 93 is a bearing which ishoused in a bearing pocket in gimbal bracket 69, and there is a centralbolt which runs through the inner-race of the rotary bearing which has astop nut as shown. Again, the mirror bearing assemblies define two axesas shown in FIG. 7. The end gimbal arm 91 attaches to bearing assemblypost of X axis bearing assembly 93 with a set screw in end gimbal arm91. The end bearing assembly 92, which is a duplicate of the X axisbearing assembly 93, and the post of the end bearing 92 attaches tojoint five 70, through a set screw in the body of joint five 70.

FIG. 8 shows joint five 70 and joint six 80 without the motor. Baseplate of joint five 70 is attached to linear bearing 71, rail of jointfive linear bearing (not shown), is attached to base plate of joint five70 with joint five linear bearing screws (not shown). The body of jointfive linear bearing 71 is attached to joint five Bellofram cylinders 72through mounting plate 73, which is attached with joint five linearbearing screws 74, which is then attached to the center rod of the jointfive Bellofram cylinder 75. Joint five locking nut 76 locks the centerrod of joint five Bellofram cylinder 75 in place. Again, there are twocylinders working in opposition in order to provide push-push motion forjoint five 70. Top gimbal bracket 69 and bottom gimbal 84 are shown inFIG. 6. Top gimbal bracket 69 attaches to top plane control arm 40 andbottom gimbal bracket 69' attaches to bottom plane control arm 50.

Joint six 80 of the system is shown in FIG. 8. Joint six 80 is notcomplete in this view. Joint six 80 is a housing for a tool comprising aclamp with a slot 81, as shown. There are threads 82 which mate with alock nut (not shown). Provided is a groove for an O-ring belt drive 83.Joint six 80 is mounted to mounting bracket 76 through a bearing. Jointsix bracket with clamp 76 is attached to mounting plate 73, as shown.Joint six bracket with clamp 76 can clamp the end of the motor with apulley at the end of that motor shaft (not shown). Within that pulleywould be attached the O-ring that would drive and mate up with O-ringbelt drive 83 and provide rotational motion.

FIG. 9 is an overview of the drive train. There are five identicalstages of push-push cylinders. Again, the Bellofram cylinders arestacked together. A close-up view of this drive train, showing onestage--the top stage--is shown in FIG. 10. Base plate for top stage 100is shown. Top stage Bellofram 101 is mounted to base plate for top stage100 through foot mounting device 102. Rod of top stage Bellofram 103 isattached to spacer and motor mount 104, and tightened down with centerrod nuts 105. It is noted that there is a complimentary Belloframconfiguration on the aft side of the stage. The motor 106 is made up oftwo portions, magnet portion 200 and moving coil 201. Moving coil 201moves back and forth in the gap of magnet portion 200, as anyconventional linear motor would move. Cable 202 delivers the voltage andcurrent required to move coil 201 back and forth. Any motor can be usedin this case, such as a linear motor, ball screw, lead screw, rotarymotor, or the like, in order to provide linear motion. There is anencoder 300, attached as shown, which provides for very precise quartermicron resolution positioning. An encoder 300 suitable for use in thepresent invention is available from Micro E Devices. In this particularcase, this is an optical device using a laser system. Magnet portion 200is attached to base plate 100 via magnet attaching screws 203. Motormount 104 is attached to moving coil 201 through coil screws 204 tomoving coil plate 205. Finally, moving coil plate 205 is attached tomoving coil 201 via plate screws 206.

This arrangement is duplicated for the each of the five axes going outto end rotary joint which is provided by a motor at the end, or jointsix 80. These all stacked together as shown in the overview of the drivetrain in FIG. 9.

The present invention can be used for surgical procedures, as amicro-assembly tool, or the like. FIG. 11 is a block diagram of themaster-slave system. There are two main parts of the master-slavesystem, the master 208 and the slave 210, which work together. Master208 is grasped at the end of joint six 80, as is shown in FIG. 1 byhuman operator 212. There is a tool 214 attached to the holder at theend of joint six 80 of the slave 210. Tool 214 can be anything fromsmall grippers to surgical tools, like microvitrectomy tools for eyesurgery, very small shavers and cutters, and tools that are used forear, nose and throat surgeries, or other similar devices. When tool 214is used, it is placed on the end of slave 210. Master 208 has a handlethat sticks out of the tool holder, such as a rod that the user holdsonto. As the operator, whether a surgeon or someone in amicroelectronics fabrication facility, moves the end of joint six 80,the movement back drives the motors, which cause the encoders to readdifferent positions 222 in each of the motor joints and they also impartforce onto the structure which is sensed by the force sensors 224 withinthe structure. The force sensors 224 and the encoders act to sendsignals to the computer 226, which then reads those values and appliesvarious filtering by filter 216, gain, adjustments to either increase ordecrease scaling 218 of those values, and sends the enhanced signals tothe slave controller 220 that drives the slave 210. The signals, whichare in the form of voltages, instruct the amplifiers that drive themotors for the slave to move in a certain direction. Slave 210 also hasa set of slave encoders 228 and slave force sensors 230. As it iscommanded to move, it will interact with its environment, whether it behardware for microelectronics or for surgical patients, it will senseany kind of contact forces, When it does so, it will again send a signalback to the computer 226 as described before, which is then reflectedback to the operator 212. The motors for the master device are driven bythe scaled signals and the operator then senses contact with a hardsurface, such as a bone or a microelectronics part. An important part ofbeing able to operate in a microscopic environment is using amicroscope. This entire apparatus will be used under a microscope sothat the operator can see down to the micron scale and view the motions.The operator 212 can control the motions in a correct direction toprevent collisions and provide proper motion. The computer 226 not onlytranslates signals from master to slave and slave to master, but alsocoordinates the joints of each of the master and slave. There arekinematic and dynamic models loaded into the computer 226 thatstabilizes the system and also provides coordinated six degree offreedom motion. So as discussed previously, a circle drawn on a pagerequires coordinated kinematic transformation matrices that are part ofcontroller.

When a hydraulic design is used in the present invention, it is arrangedsuch that the master and the slave apparatus is configured small enoughso they do not obscure the work space for very small operations. If adoctor or fabricator is dealing with very small operations, then he/shedesires not to have a very large apparatus sitting next to the patientand/or the microelectronics fabrication site. Therefore, the hydraulicsystem is designed to place the entire motor drive unit in a remotelocation. An example of Belloframs suitable for use in the presentinvention are commercially-available units by Bellofram, Inc. Company.However, in an alternative embodiment, the Belloframs can be in encasedbellows. These bellows are closed off at one end and placed inside of atube. The space between the bellows and the tube is filled with waterand duplicates a Bellofram. A control rod would come out from the closedoff end plate of the bellows and act to drive the system. The bellowsalso provide a spring force, which is sometimes disadvantageous becausethe spring action of the bellows would also give stored energy to thesystem which typically is not something desirous in a surgical platform,primarily because if the power goes off, spring force would then relaxand could cause unexpected motion at the end of the tool. Belloframs incontrast are folded membranes that do not store energy in that fashion.

The present invention is a robot system, or motor servo controlledapparatus which is indirectly commanded by a computer. In thisparticular case, the motor servo controlled apparatus utilizes a mastersystem so it is not computer controlled directly. The apparatus can becontrolled by the computer to command position, velocity, andacceleration so that the user could pick up a part at one location andplace it in another location all within a very small work space. Thetotal work space of the robot system can be approximately a sphere witha diameter of 1.5 to 2 inches. The embodiment can be made of aluminumwith metal bearings. The components can be made out of other knownmaterials to either reduce weight or to potentially use the devicewithin a magnetic environment, such as a magnetic resonance imaging(MRI) system. In this manner, a doctor could perform surgery whileviewing inside the body of a patient.

The fluid within the hydraulic system can be water, oil, or othersuitable fluids know to those of skill in the art. The master-slavearrangement can be a low pressure system similar to a car brake systembut can be configured using hydraulic power units at higher pressuresand using hydraulic servo valves to control the system. The Belloframscan be replaced/exchanged with hydraulic cylinders. However, hydrauliccylinders have high friction associated with them. When dealing withvery small micron range force and positions, the system has to bedesigned to build up pressures to overcome the friction and then, oncethe friction is overcome, the device would noticeably jerk. Because thesystem has force sensor and position sensor or encoder, tremors withinthe operator's hands are sensed, characterized and removed from thesystem so that very smooth operating motion would be seen at the slavedevice as a commanded motion. Other things that the controller orcomputer system can provide are methods for controlling the maximumvelocity and maximum acceleration systems so that the operator can movevery quickly with his master but those motions would not be translatedto the slave, necessarily, for safety purposes. Furthermore, otherthings that the controller or computer system can provide for aregravity compensation to enhance the dexterity of the operator. Thesoftware that operates the controller and provides motion commands tothe manipulator should be programmed such that forces due to the effectsof gravity on the robot and payload are completely compensated in allpositions and orientations (translations and rotations), i.e., thedevice will be weightless. If master is released by the operator withoutany breaks, regardless of load orientation, then the load will besupported and will not experience the forces of gravity (the forces ofgravity become negligible). The operator will then experience lessfatigue by not having to support the mass of the robot and payload,which will increase the precision of the operator during the procedure.Only forces from contact of the tool and the workpiece (e.g., humantissue) are reflected back to the master in the form of force feedback.

The computer system can also be used to record all motions during asurgical operation and then played back to the master system with arecorded visual record for training purposes. A resident or intern(i.e., anyone less experienced) could look through a microscope and seethe actual surgical procedure that occurred and also to be able to feelthe motions that were imparted during the surgery. This would be similarto a fight simulator for training pilots or an automobile retrofittedwith dual steering mechanisms for driver education. A means of recordingare provided such that the command (motion) signals sent from the masterare recorded so that manipulative tasks can be played back forsubsequent use. The more experienced operator will use manipulator andplay back the recorded commands for those in training; thus, the lessexperienced operators are allowed to experience the commands and motionsexperienced by the more experienced operator, which were recordedearlier in time. Any means of recording will suffice, including but notlimited to the audio track of a video recorder, optical disk, digitalvideo disk, CD-ROM, MOD, analog or digital tape, PCM tape, etc.

The computer system can also be used to operate the manipulator in adual control mode: (1) first mode and (2) second (delta) mode. In thefirst mode, the expert performs the task at hand and the lessexperienced operator views the actions through some means. Two mastersare used to control one robot. The motion commands are added (summed)with no weighting, which enables either of the two masters to assumecontrol (both masters act to send motion commands). The masters areoperated in a force reflecting or feedback manner. If one master moves,then the other master moves. In the second mode (delta mode), the lessexperienced operator performs the task at hand, while the moreexperienced operator is able to take corrective action to compensate forthe actions taken by the less experienced operator. Any change or forcesexperienced by the less experienced operator are also felt by the moreexperienced operator, thus allowing the more experienced operator tocompensate accordingly.

Examining a single axis of the system, there is a set of hydrauliccylinders arranged in a master-slave system similar to those found onautomobile brakes. Driving the master cylinders is a servomotor whichhas connected to it encoders and force sensors, which can be pressuretransducers that measure the pressure within the hydraulic line. Themotor, master-slave cylinders with connecting fluid lines, and sensorsmake up a drive unit. Six drive units are used for the 6-DOF master, andsix drive units are used for the 6-DOF slave. As the operator pushes onthe hydraulic cylinder of the single axis, as an example, both forcesand position displacement are sensed by the system. Those signals aresent to the computer, which then scales those values in appropriatemanners to either down scale motions for the slave and/or change theforce levels that are applied by the slave. The slave itself iscontrolled by the computer as well as a motor amplifier which senses theposition and forces sensed by the slave. It is also provided with thecommand position and force information from the master. These commandforces and positions are translated to voltages, sent to the motors forslave, slave motors then move to comply with the command values and theslave cylinder moves. If it contacts the surface within its environmentthen it corresponds to the action of the master, then it sends the forceand position information back to the computer which then sends thatinformation back to the master unit so that operator of the master unitcan then sense what the slave unit is sensing. The present invention isa force reflecting master-slave manipulator. The slave is reflectingback the signals to the master and then to the operator, based oninitial command positions and forces sent by the master. In a sense, itcan be likened to a brake pedal in a car where a person will push in thebrake of the car, the brake pads would clamp on the brakes of the car,and the forces of the clamping are sent back to the driver so that thereis a sense of resistance associated with the brakes clamping down on thediscs or the drum of the brake. Additionally, if the brakes of the carseize for some reason because of irregularities on the braking surface,these irregularities would be sent back to the pedal of the brake andwould form vibrations which could be detected by the driver. An additionto this analogy in the present invention is a computer system thatcontrols the motors.

Other variations and modifications of the present invention will beapparent to those of skill in the art, and it is the intent of theappended claims that such variations and modifications be covered. Theparticular values and configurations discussed above can be varied andare cited merely to illustrate a particular embodiment of the presentinvention and are not intended to limit the scope of the invention. Itis contemplated that the use of the present invention can involvecomponents having different characteristics as long as the principle isfollowed. It is intended that the scope of the present invention bedefined by the claims appended hereto.

We claim:
 1. A master-slave micromanipulator method, comprising thesteps of: moving a master dual planar structure, comprising the stepsof:(a) providing a master frame; (b) providing a first master X-Y stageattached to said master frame; (c) moving said first master X-Y stage inboth an X and a Y direction in a first master X-Y plane relative to saidmaster frame; (d) providing a second master X-Y stage attached to saidmaster frame; (e) moving said second master X-Y stage in both an X and aY direction in a second master X-Y plane relative to said master frame,said second master X-Y plane being oriented substantially parallel to,but not coincident with, said first master X-Y plane; (f) generating amaster coordinated X and Y and orientational output comprising moving amember connecting both said first master X-Y stage and said secondmaster X-Y stage for coordinating motion of said first master X-Y stagewith motion of said second master X-Y stage;moving a slave dual planarstructure, comprising the steps of: (g) providing a slave frame; (h)providing a first slave X-Y stage attached to said slave frame; (i)moving said first slave X-Y stage in both an X and a Y direction in afirst slave X-Y plane relative to said slave frame; (j) providing asecond slave X-Y stage attached to said slave frame; (k) moving saidsecond slave X-Y stage in both an X and a Y direction in a second slaveX-Y plane relative to said slave frame, said second slave X-Y planebeing oriented substantially parallel to, but not coincident with, saidfirst slave X-Y plane; (l) generating a slave coordinated X and Y andorientational output comprising moving a member connecting both saidfirst slave X-Y stage and said second slave X-Y stage for coordinatingmotion of said first slave X-Y stage with motion of said second slaveX-Y stage; and,mimicking and scaling down said master coordinated X andY and orientational output to said slave coordinated X and Y andorientational output.
 2. The method of claim 1, further comprising thestep of moving a first gimbaled arm affixed to the master dual planarstructure along an axis of the first gimbaled arm and mimicking andscaling the movement along an axis of a second gimbaled arm affixed tothe slave dual planar structure.
 3. The method of claim 2, furthercomprising rotating the first gimbaled arm about its axis and mimickingand scaling a rotation along an axis of the second gimbaled arm.
 4. Themethod of claim 2, wherein the step of mimicking comprises providingpush-push apparatuses.
 5. The method of claim 3, wherein the step ofscaling comprises providing a programmed computer.
 6. The method ofclaim 2, further comprising the step of feeding back a signal from thesecond gimbaled arm to the first gimbaled arm when the second gimbaledarm contacts a surface.
 7. The method of claim 2, further comprising thestep of filtering tremors experienced between said master dual planarstructure and said slave dual planar structure.
 8. The method claim 2,further comprising the step of compensating for the forces of gravityexperienced by the first gimbaled arm and the second gimbaled arm. 9.The method claim 2, further comprising the step of recording and playingback a plurality of commands exchanged between said master dual planarstructure and said slave dual planar structure.